Vinyl esters



1940 I f .w. J. TOIUSSAINT I 2,186,437

VINYL ESV'IVERS Filed Nov. 11, 1936 ACETYLENE ow o'FE ACID Q "Aclo if" g 4 RECYCLED PRODUCT I (RESIDUE FROM'FIRST snu.)

PRODUCT H RECOVERED ACID CONDENSER ACETALDEHYDE E ETHYLIDENE ,DIESTER VHYDROLYSIS I AclplFlEo w M I 1 ETHYLIDENE v x E DIESTER I 55mm: Sm ETHYLIDENE I AIR OR 0 DIESTER s'roRAc v Y ACID ACID I ACETIC v v f ACID I I I I I ACEIIC 'ACID E V II ATTORNEY 1 phoric acids were specifically shown for'this pur- Patented Jan. 9; 1940- 7 2,180,431. e QVINYE fFs E S: 1 j

Walter J; Toussainnbharleston, W vy, asaignor to Carbide andcarbon Chemicals Corporation,

a corporation of New York Application November 11.1mm, Serial N6."11o,'z1o n Claims. -(Cl.; 280- -498)' V This invention presents improvements in the; process of making vinylesters"through the rein the action of acetylene with carboxylic acids presence of mercuric catalysts.

The reaction between acetylene and carboirylic acids to form ethylidene diesters zagndjvinyl esters was first disclosed by Kla'tte in 1913. [His teachingsincluded the use' of mercury compounds to catalyze the reaction, and the use of catalytically acting 7 substances, such as. mineral acids; sul'-; j i'onic acids and acid salts; in"ccnjunctioniwiththese m c ata y ts. .Suliuric a fi r pose. Many variationsof Klattes original process have beenlproposed, but none of these has;

departed from his teachings in the essential particulars of the reaction,'and, to thistime'QtheQ best available catalysts for promoting the cornbination of acetylene with carboxylic acids have; remained those essentially derived 'from mercury "compounds and sulfuric acids.

The object of my invention is to provide catalytically acting acid substances for use inKlatte's process which are capable'of promoting a smooth' reaction between acetylene and variouscarbox ylic acids, and to make possible the economical andeflicient production of vinyl esters in yields greater thanthose previously-"obtainable fromthis reaction; My invention includes a generally improved process for making-vinyl esters, in

' particular the acetate; 1

These ends may be attained through the -use of catalytically aetingacid substances essentially composed of heteropcly acids in conjunction with,-

mercurycompounds as catalysta -In the presence of these new catalysts,,I have found that:

quantities of vinyl esters can be produced per unit of mercury usedwhich are greatiy inexcess of those which can be obtained in the presence of mercury compounds and sulfuric acid. I The bodies designated hereasheteropoly acids 7 are best; described as complex inorganic substances of high molecular weight in which two or more different acid cations, or oxidesoi metals or metalloids, are associated withvarying, and

frequentlyindeterminate. amounts of: combined water and wate'rof hydration. The molecular size of these bodies may be as great as 3000, and they function as polybasic acids; apparently pos sessing from to 10 orjrnore acid hydrogen" 'for sixteen hours. At the end of this period, the

atoms. Little-is known to the actual consti--:

tution of the heteropoly acids, but they probably include anuclear cation, 'such as an oxide 01 phosphorus, silicon, boron'or-arsenic, coordinated with a group "of other cations which-may 5 be oxides of tungsten. molybdenum; vanadium,

' chromium; sulfur. selenium;-- tellurium, or one- 0f the first named group other than-thatoi the nuclear element. early all of the-heteropolyfl acids are quite' soluble in water.

-Heteropoly' acidscan be formed by reacting salts andacids' oithe different metals or-metal loids' to beincluded in the complex. This reac-- tion' maybe eiiected by heating these materials in aqueous 'solution,"aiter which the mixture can.

be acidified with a strong acid,and'the'heteropoly' aeidformed-can beextracted with a water-im-' miscible solvent. For e'xample, tungstomolybdophosphoric acid was made by dissolving 100 par-ta by weight of sodiun'i tungstate -and'25 parts by weight of sodiummolybdate' in 700 par-ts "b 9. weight of water. To this solutionwas added 845 parts byweight of 85% phosphoric acid and- 119 parts by weight of C.- -P. hydrochloric acid.

The entire mixture was thenheated at 100 C; 26

mixture was further acidified-with hydrochloric "acid,- an'dstirred with ethyl ether. Three-phases formed. and th'e'lower'layer was. withdrawn and evaporated to obtain the -tungstomolybdoplios.-' phoric acid. Silicotungstic, borotungstic, phosphotungs'tic, silicomolybdic, phosphomolybdic and other heteropoly acids suitable for .use in this invention have been prepared=by similar .pro

cedures. l The actual catalystused for carrying-the .re-;

action between acetylene and carboxylic acids to. make vinyl esters'is preferably made by precip T itating mercury by means. of acetylene passed /into a solution of mercuric acetatein acetic acid 0 iorflother mercuric carboxylate in the corre- 'sponding acid), andthereaifter adding theheterropoly acid. This catalyst I is active immediately upon'preparaticn. I The method of preparingthe catalyst, and the proportions of catalyticmaterials'used' for its preparation; will vary somewhat depending on the'temperature at which the reactionflis to be, conducted. For use at low ternperatures,.;such as fromabout 15 to 350" 0.,

equal weight quantities of mercuric oxide{as such u or in the form of the mercuric carboxylate, and

- the heteropoly acid should be used, while at v by dissolving higher temperatures of, say, about 50 to 105 C., only one-half as much heteropoly acid should be employee.

Other methods for preparing the catalyst may be employed. For example, one part of heteropoly acid, such as silicotungstic acid, may bedissolved in 100 parts of carboxylic acid, and the solution saturated with acetylene. One part of mercuric carbo'xylate dissolved in the carboxylic acid is then added to the first solution. This catalyst is useful at higher temperatures from about 50 to 95 C., and becomes active after a brief inductionperiod of comparative inactivity. A less desirable form of 'the catalyst may be made mercuric oxide in the 'carboxylic acid and adding theheteropoly acid to this solution. The mixture is. then stirred under an at-- mosphere of acetylene at 50 to 75 C. for a short time. The catalyst may be used at 70 to 75 C., and it assumes activity after a brief induction period.

The exact .nature of these catalysts is not known,'but they apparently are not simple inorganic salts of mercury and the heteropoly acid used. Most probably, the catalysts are more complex organo-met'allic substances, or mixtures of substances, which exist asgel'atinous masses.

The quantity of the catalyst used for the reaction may vary greatly. In general, the mercury compound (calculated as the corresponding mercuric carboxylate) should be equal to-at least 0.005%," and"preferably from aboutf0.25% to 1.0%, by weight of the carboxylic acid maintained. in the reaction, and the heteropoly acid.

should be employed in an amount ranging from one-half to about equal that ofthe mercury compound, according to the temperatureat which it is-tobe used. Larger quantities of catalytic materials maybe used, but are unnecessary.

intoian-ag itatedbody of the carboxylic acid con- In carrying out the reaction to obtain vinyl esters, the-new catalysts may v V to any-of the known-methods'of reacting acetylene with carboxylic acids. For example, the oarboxylic acid containing the catalyst may be saturated with acetylene, followedby distillation of J the reaction mixture to isolate the product.

Alternatively, the preparation-of vinyl esters may a be carried out continuously" by passing an excess of. acetylene through a body of carboxylic acid 0. The catalyst is prepared asdescribed, using the appropriate proportions of materials and procedure for the portion of this temperature range: in which thereaction is to be conducted. An operating temperature of about 35"v C. is generally preferred; Acetyleneis then passed 'taining the catalyst Absorption of'acetylene is quite rapid, and a slight blow-off of gasis maintained in order to prevent excessiveaccumulation of inert gases in the reaction zone. Mechanibe used accordingv cal. stirring devices may provide the agitation desired, or it can be obtained by introducing the gas stream through diffusers into the body of liquid. A portion or the reaction mixture is withdrawn either continuously or periodically from the reaction zone, and passed to a still for the recovery of the 'viriylester. The reaction is sup- .plied' with fresh carboxylic acid to compensate for the liquid withdrawn.

The vinyl ester is, obtained as a distillate from the reaction mixture in the first still, and the residue, composedio'f the carboxylic acid together with some ethylidene diester, may be returned to the reaction, or treated separately in a second still. I prefer to'pass at least a portion of. the residue to a second still,. where the carboxylic acid is obtained as-a distillate and returned to the reaction, and the ethylidene diester is separately recovered. The ethylidene diester may be used as such, .or it may be hydrolized, for example, by: distilling it with water containing a strong acid. The products of hydrolysis are acetaldehyde andthe carboxylic acid. Of these, the latter may bereturned to the reaction for reuse in the process, and the former can be treated further with oxygen or air to yield acetic acid. In the vinyl ester: to be produced in the process is vinyl acetate, the oxidation of acetaldehyde yields still further quantities of acid for use in the original reaction.

It is occasionally necessary to replenish the catalyst. in the reaction mixture, and additions ofsmall quantities of either the mercury carboxylate or heteropoly. acid will, in some cases, serve this purpose, but the addition of both is usually preferable. 7

When the catalyst usedin this process is to be replaced, it is desirable to recover the constituents of the spent catalyst, 'and I have provided means for carrying this out efll'ciently and economically. Recovery of the catalyst constituents includes, first, separation of the catalyst from the reaction mixture, and, second, chemical treatmento'fathe separated catalyst to convert it again to mercuric oxide and theheteropoly acid.

Separation of.,the catalyst may be accomplished by filtering or by centrifuging the reaction mixture, or, preferably, by distilling the mixture toleava a solid, dry residue of the catalyst material in pulverent form. The separated material may then be distilled, at reduced pressures, to drive off the mercury, which is recovered as a distillate,lea ving a residue of oxides of the ele, ments of the heteropoly acid. The mercury can then=be converted'to mercuric oxide through its nitrateor chloride, and the oxides of the elements of the-het'eropoly acid may be treated with sodium hydroxide solution to form a solution of sodium salts of those oxides. The latter then can be treated as previously described to form the heteropoly acid. Alkalies other than sodium hydroxide also may be used to, form soluble compounds of the elements of the heteropoly acid present. I I

Recovery of the catalyst materials may be carried out periodically, or in more or less continuous fashiomby treating portions of the withdrawn reaction mixture.

A few specific examples will now be given to illustrate the salient features of my invention. In these-examples, proportions of materials are expressed gravimetrically. In each of the following'examples, the preparation of vinyl acetate from acetic acid and acetylene will be described :aceticuacid and mixed'withamacetic cid tion of the heteropoly acid .at}.abput 5 for comparative purposes; b ut'it will be-tunderrz stood that other vinyl aliphatic esters can be; similarly prepared by .replacing acetic i'acid' 'withl 'forinic, propionic, butyricor-other carb oxylie-a- Y acid. In the ease ofihigher carboxylicracidsythe1;" 'DIOCQSS gives best resultsif the catalystisiorrn'ed 'from'the mercury compound and heteropolyacid' in abody or alower'carboxylic acid;fsuch asacetic acid. The: preformed catalyst in' the: lower acidiis then added to the higher molecular weightacid; and thefadditiorrof acetylene'car'i'iedout. as described? This procedure haszi proved to be satisfactory-in making .vinyl esters. of 2.-ethylbutyric= p acid and the 1ike.-' v I i Examplez i iiieach -.ei perirnent operation o e v 1 ed in process; the. 1,mercurlc:=- oxide was -di treatment. resulted in the formationyoi; ax=pre= cipitateg' Thegmixtur'e was, then 'stirred under. acetylene tor the period indicated. at-48 f to,52. n: h

The amounts of; acetylene absorbed d 7 period andfor the last hourof. operation (areshown. Generally; the. initialv absorption 'was.* rather. low: duringthe induction period. required,

for suchcatalysts, as pointed out above.

ately to recovertheproducts'formeds In one experiment, sulfuric. acid. was used in place of the heteropoly acid. .to afford acomparison of the results obtained; RunNo 1 2 3 .4 l 5 6- Mercuricoxideunflpartsu 2 4 4 4 a 4 4 Heteropoly acid d 2 I 4 3 4 a 4' Suliuricac' do ..L '5.I Aceticacid... do.-... 404 .420 400 4116 4399 Temperature..;,. 48-52 48-53 48-52- 48-52 48-52 48 -52 Duration hours 6 6 5 6 11 i 5 Acetylene absorhed-parts:' V H Last hour of operation. 12.3 12 1.7 0.5 0 j 0 Total 47 47 as is l6 Produetsparts: i

' Vinyl acetate 111 127 96 58 90 50- Ethylidene diicetate... 37 i3 27' Trace '18 Aoetaldehyde.- -2.4 A 2.5' 8.2. 1.4. -'7 Recovered aceti 289 299 350 .339 352 Re lie. 7 l0 9 8.4 l0

Not determined.

The only variatlon'in procedure carrying out these experiments was in3the case of No. 6, in which the. sulfuric acid was added in three portions of 1.7 parts'ea'ch at the start and;

at the end of the third and fourth hours.

The'heteropoly acids usedawere a Run No. "1-Silicotungs tic acid.

Run No. 2--Phosphotungstic acid; v

Run No. 3--Silicomolybdic acid." Run No. 4-Phosphomolybdic'acid. 1 I

Run 'No. 5Tungstomolybdophosphorlc' acid.

- I Example 2 the catalyst.

acid was then added; and: thetreatmentwith acetylene was continued. Rapid absorption of the gas took place immediately.

The product of the reaction was distilled'pt a pressure of about mm. oflmercury, and the-1. distillate and residue were. tractionateda separa,

place that removed in the distillation;

- Temperaturev Example '1, to recover; products.

"Acetic acid..; .Aceticanhydride.

" Temperature.

hour ofoperation Acetaldehyde. Recovered acetic aci acids used in1-these'- experiments Run N io.iPhosphoniolybdlc-acid. RunINo.: 1l-fTungstomolybdophosphoric acid RunNo.;-.12'-Sulfuricacid.- Q;

' ln' two portions. or 1137 and: 1.5,:parts; ati the' s'tart': and; at the beginning" of? thesecondf hgur'" of Lope eration, respectively. Also;..a. small; quantity of acetic anhydride 'wasius'ed 1a this experiment.

InRun No. 12,. the; sulfuric, acid was addedf three portions off 1.7 parts'each at-the start. and at the l beginning of the third and? fourth hours a of ioperatiorifi During the last hour of operation in Run No; '12; the mixture 'was heated to 5o? Examp 7 4 4 f l were the InRunJNo'. 8; the Irotungstic acid was added ff,

In the operation 01'. the new processlin'theiollowing experiments; a. semi-continuous system "ofl operation was-followed. The-'catalysts werea'pre pared-1 as indicated'in Example and-the vinyl acetatewas distilled out of the reaction-mixture,-

after each'one' hour-=peri'od of acetylene absorp! I tiongat' the reaction temperature and at a pres- Mercuricoiridenlll; ;f.parts; 4" 4 Phosphotungstic acid. do Sulfuric acid Y Duration s at a sure'ot 35 of mercury. fAdditional acetic P acid 'was" added to the reaction mixture'to reh 65 In carrying out the process inRun No.14; the

sulfuric acid wasadded in two portions of 3,731

parts. each at the start and. arm the third; hour of operation. Thevarlous heteropoly acids used 'in-the eic'periments are, for the most part, available commercially, although equivalent material can, be inade. following the procedure previously ,dey scribed for the preparation: of tungstomolybdophosphoric acid] Efor 1. example; the phospho- Equivalent material to this product was made by stirring together 36 parts of molybdicacid, 3

parts of sodium phosphate and 100 parts of water at 100 C. for 17 hours, followed by the. addition of hydrochloric acidandextraction with ether. The silicomolybdic-acid used was prepared by stirring together 12 parts of sodium silicate monohydrate and 36 parts of molybdic acid in 200 parts of water for 42 hours at 100 C. 1 This mixture was acidified and extracted with etherto obtain the heteropoly acid, The phosphotungstic acid used was a commercial product which'was stated "to have the formula j P205.24WO3.XH2O

Ihe borotungstic acid'used' likewise was a commercial product identified only byaits specific gravity of 2.6 to 3.0. The silicotungstlc acid employed wasa commercial product, and equivalent material was prepared by reacting together+112 parts of sodium tungstate dihydrateand 10 parts of sodium silicate monohydrate in 200parts of water at 100 C. To this was gradually added 119 parts of C. P. hydrochloric acid. The mixture' was then cooled and stirred with diethyl ether. Three phases formed, the lowest oi'which was removed and evaporated to recover the silicotungs'tic acid. 7 g

modifications in the process described arev possible without departing from the essential ieatures of 'my invention, and such modifications are included within the invention as defined by the appended claims;

I claim:

1. Process which comprises reacting acetylene with ;a carboxylic acid in the presence of a mercury compound of a heteropoly acid.

2. Process whichcomprises reacting acetylene with a carboxylic acid in the presence oi a mercury compound of a heteropoly acid, and recovering a vinyl ester from the reaction product.

3. Process which comprises reacting acetylene with an aliphatic carboxylic acid in the presence of catalytically actingnquantities of a mercury compound or a heteropoly acid..

4. Process which comprises reacting acetylene with a lower fatty acid in the presence of a mercury compound of a heteropoly acid.

5. Process for making vinyl esterswhich comprises reacting acetylene with carboxylic acids in the presence of a mercury compound of a heteropoly acid at a temperature between about and about 105 C.

6. Process for making vinyl esters which comprises reacting acetylene with one of the group consisting of formic, acetic, propionic, butyric,

and z-ethylbutyric acids in the presence of a mercury compound of a heteropoly acid.-

7. Process for making vinyl esters which comprises reacting acetylene with carboxylic acids in the presence of a mercury compound of a heteropoly acid'of the group consisting of silicotungstic, phosphotungstic, silicomolybdic, phos'-' phomolybdic, tungstomolybdophosphoric, and borotungstic acids.

8. Process for making vinyl acetate which comprises reacting acetylenewith acetic acid in the presence of a mercury compound of a heteropoly acid.

9. Process for'making vinyl acetate which comprises reacting acetylene with acetic acid'in the presence of a mercury compound of silicotungstic acid.

10. Process for making vinyl propionate which comprises reacting acetylene with propionic acid in the presence of a mercury compound of a :heteropoly acid.

" lene with a. carboxylic acid ,inthe presence of a mercury compound of a heteropoly acid, distilling the vinyl ester from the reaction product, thereafter distilling the carboxylic acid from the residue of said reaction product to form a residue returning to the'reaction both the 'carboxylic with carboxylic acids which comprises treating a solution of a mercury compound in a carboxyllc acid with acetylene and a heteropoly acid.

15. Process for making catalytically acting substances i'or promoting the reaction of acetylene with carboxylic acids which comprises treating a solution of a mercury compound in the carboxylic acid with acetylene to form a precipitate,

and thereafter adding a heteropoly acid to the mixture.

16. Processior making catalyticaliy acting substances for promoting the reaction of acetylene with carboxylic acids which comprises dissolving a heteropoly acid in the carboxylic acid, treating the solution with acetylene, and thereafter adding a mercury compound to said solution.

17. Process'for recovering catalytic materials from reaction mixtures containing mercury compounds of' heteropoly acids which comprises distilling said mixtures to obtain mercury as a distillate,land thereafter treatingthe residue with alkali to form soluble compounds of the elements of said heteropoly acid.

18. Process for making catalytically acting substances for promoting the reactionof acetylene with carboxylic acids, which comprisesseparating a mercury compound of a heteropoly acid from mixtures containing it by heating said mixtures to separate mercury as a distillate, treating the residue with alkali toform soluble compounds of the elements'oi said heteropoly acid, treating said soluble compounds with strong mineral acid to regenerate the heteropoly acid and recovering the regenerated heteropoly acid by the aid of awater-immiscible solvent, forming a solution of a mercury compound in a carboxylic acid, and thereafter treating said solution with acetylene and the regenerated heteropoly acid.

WALTER J. 'IVOUSSADIT.

. acidrecovered and that liberatedby hydrolysis.

'13.-In a continuous process for making vinyl 7 CERTIFICATE OF CORRECTION. Patent No. 2,186,157. r I v January 9, 191p. WALTER J. V'TOUSSAINT.

It is hereby certified that error appears in the printed specification v of the above numbered patent requiring correction ass-follows; Page 1, sec- 01166011111111, line h9, for "550 0.." read 55 C.'; page 2, second column, line.

27, for the word "In" read If; and that the said Letters Patent should be reed with this correction therein that thesame may conform to the record of the case in the P tent Office. i

Signed and sealed this 15th day of "February, A. D. 1910.

v Van Arsdale, (Seal) Acting/Commissioner of Patents. 

